// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/disk_cache/blockfile/mapped_file.h"

#include <errno.h>
#include <sys/mman.h>

#include "base/files/file_path.h"
#include "base/logging.h"
#include "net/disk_cache/disk_cache.h"

namespace disk_cache {

void* MappedFile::Init(const base::FilePath& name, size_t size)
{
    DCHECK(!init_);
    if (init_ || !File::Init(name))
        return NULL;

    size_t temp_len = size ? size : 4096;
    if (!size)
        size = GetLength();

    buffer_ = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED,
        platform_file(), 0);
    init_ = true;
    view_size_ = size;
    DPLOG_IF(FATAL, buffer_ == MAP_FAILED) << "Failed to mmap " << name.value();
    if (buffer_ == MAP_FAILED)
        buffer_ = 0;

    // Make sure we detect hardware failures reading the headers.
    std::unique_ptr<char[]> temp(new char[temp_len]);
    if (!Read(temp.get(), temp_len, 0))
        return NULL;

    return buffer_;
}

void MappedFile::Flush()
{
}

MappedFile::~MappedFile()
{
    if (!init_)
        return;

    if (buffer_) {
        int ret = munmap(buffer_, view_size_);
        DCHECK_EQ(0, ret);
    }
}

} // namespace disk_cache
